The present invention relates to an image reading apparatus for reading image information of an original and an illumination apparatus used in the image reading apparatus.
There is conventionally known an image reading apparatus for illuminating a transparent original and reading its image, as disclosed in U.S. Pat. No. 5,038,227. The conventional image reading apparatus will be described with reference to FIGS. 7A and 7B.
FIG. 7A is a sectional view showing an image reading apparatus, and FIG. 7B is a perspective view. A bar-like fluorescent tube 700 is attached to the end of a light guide plate 701 which is arranged in parallel to a platen glass 702 for supporting an original. The light guide plate 701 is a resin light diffusion panel for diffusing light emitted by the fluorescent tube 700 and emitting the light from the surface.
The platen glass 702 is an original table for supporting a transparent original such as a photographic film. A transparent original on the platen glass 702 is sandwiched and fixed between the light guide plate 701 and the platen glass 702. A CCD 703 is a linear imaging element for converting image information into an electric image signal. An imaging optical system 704 optically guides the image information of the transparent original to the CCD 703.
A carriage 705 supports the CCD 703 and imaging optical system 704, and is movable in the subscanning direction along guides 706 and 707. When the entire surface of a transparent original is illuminated by the light guide plate 701, image information of the transparent original is read by the CCD 703 via the imaging optical system 704. The carriage 705 is moved in the subscanning direction to sequentially read the image of the entire transparent original.
If, however, dirt or dust exists on a transparent original or a film surface is scratched, the conventional image reading apparatus reads even the dirt or scratch, so the image degrades owing to the dirt or scratch.
The present invention has been made in consideration of the above situation, and has as its object to provide an image reading apparatus and illumination apparatus capable of preventing degradation of an image caused by dirt, a scratch, or watermark information on an original surface.
To overcome the conventional drawbacks and achieve the above object, an image reading apparatus according to the first aspect of the present invention has the following arrangement.
That is, an image reading apparatus is disclosed that forms light from an original into an image on a solid-state image sensing element by using an imaging optical system, and reads image information of the original. The image sensing apparatus comprises a first light source for emitting light of a visible region, a second light source for emitting light of an invisible region, and a light guide plate. The light guide plate has the first and second light sources at an end face, guides incident light from the end face along a surface, and emits the incident light from the surface. The image sensing apparatus further comprises image information reading means for reading the image information to the solid-state image sensing element, and light from the original illuminated with light from the first light source that is guided by the light guide plate, where the image information is recorded on the original on the basis of an image signal obtained by guiding. The image sensing apparatus further comprises information reading means for reading second information to the solid-state image sensing element, and light from the original illuminated with light from the second light source that is guided by the light plate, where the second information is presented on an optical path extending from the light guide plate to the solid-state image sensing element on the basis of an image signal obtained by guiding. The image sensing apparatus further comprises correction means for removing the second information read by the information reading means form the image information read by the image information reading means.
An image reading apparatus according to the second aspect of the present invention has the following arrangement.
That is, an image reading apparatus comprises a first light source for mainly emitting light of a visible region, a second light source for mainly emitting light of an invisible region, a light guide plate for guiding light emitted by the first and second light sources along a surface and illuminating an original, and reading means for converting, into an image signal, transmitted light of the transparent original illuminated with light from the first or second light source that is guided by the light guide plate.
An illumination apparatus according to the present invention has the following arrangement.
That is, an illumination apparatus used in an image reading apparatus for forming light from an original into an image on a solid-state image sensing element by using an imaging optical system, and reading image information of the original comprises a first light source for emitting light of a visible region, a second light source for emitting light of an invisible region, and a light guide plate which has the first and second light sources at an end face, guides incident light from the end face along a surface, and uniformly emits the light.
Other objects and advantages besides those discussed above shall be apparent to those skilled in the art from the description of a preferred embodiment of the invention which follows. In the description, reference is made to accompanying drawings, which form a part hereof, and which illustrate an example of the invention. Such example, however, is not exhaustive of the various embodiments of the invention, and therefore reference is made to the claims which follow the description for determining the scope of the invention.